MEGASS AS FUEL. 



Relation between Cane ground and Requisite Heating: 

 Surface, etc. The writer has had access to essential data on these point* 

 as they occur in a large number of well equipped modern factories and as a 

 result has concluded that no average datum can be given, the variation in 

 factories, all of which were working well, being so great. In the following 

 table ' cane ' means the short tons of cane ground in 24 hours ; 1 2 square feet 

 heating surface in a smoke tube and 10 in a water tube are taken as the equiva- 

 lent of one horse power ; all surfaces are expressed in square feet : 



Ratio of 



Horse power to Cane 



Heating surface to Cane 



Grate surface to Cane 



Grate surface to heating surface 



Maximum. 

 2-4 : 1 

 24 : 1 

 1 



FIG. 222. 



As shown in greater detail in another section, the thermal value of a pound 

 of megass of fixed water content is sensibly constant, and hence it would 

 appear reasonable that a fairly constant ratio of heating surface in boilers and 

 hence of horse power would obtain ; actually, the smallest variation in this 

 ratio does obtain and the writer thinks that a ratio of heating surface to cane 

 of 18 : 1 is ample and representative of good modern practice. 



On the other hand, however, there is no reason for expecting any 

 uniformity in the ratio between grate area and heating surface ; this will of 

 course depend on the intensity of draught, a smaller grate area being sufficient 

 under forced or induced draught than under natural draught. 



As will be explained in greater detail in a subsequent section, the weight of a 

 cubic foot of megass from varieties (or even in different seasons from the same 



409 



